[10] RFR(S): 8087339: The code heap might use different alignment for committed size and reserved size

Tobias Hartmann tobias.hartmann at oracle.com
Mon Nov 27 08:14:47 UTC 2017

Hi Vladimir,

thanks for the review!

Best regards,

On 22.11.2017 21:23, Vladimir Kozlov wrote:
> Good.
> Thanks,
> Vladimir
> On 11/22/17 5:51 AM, Tobias Hartmann wrote:
>> Hi,
>> please review the following patch:
>> https://bugs.openjdk.java.net/browse/JDK-8087339
>> http://cr.openjdk.java.net/~thartmann/8087339/webrev.00/
>> The alignment of the code cache is determined in CodeCache::reserve_heap_memory() by computing the minimum of the page
>> size for the ReservedCodeCacheSize and the InitialCodeCacheSize (which is usually very small and not aligned to the
>> large page size). As a result, when using large pages (by enabling UseTransparentHugePages or UseHugeTLBFS), the
>> ReservedSpace is only backed by large pages if the InitialCodeCacheSize is large page aligned as well.
>> I've changed the implementation to not consider InitialCodeCacheSize and re-factored the code to use
>> CodeCache::page_size() both for the alignment of heap sizes as well as the alignment of the entire reserved space.
>> I've verified that this sets the correct alignment on my machine when using 2048K pages instead of 4K pages.
>> Thanks,
>> Tobias

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